Enter the password programmed into the control panel earlier so that the home alarm lets you access the menu commands. Navigate to the menu that will let you deactivate the window sensor to be disabled. Deselect or remove the check mark next to the window sensor on the "Input" menu. Rearm the system by entering the password again.
Go to the window that has the sensor attached to it. Open the window. Unscrew the sensor pad from the bottom of the window using a Phillips screwdriver. Place the sensor pad aside.
Loosen the screws on the side of the sensor-receiving plate on the windowsill with a Phillips screwdriver. Unwind the wires from around each screw.
Remove the wood screws holding the sensor receiving plate to the windowsill using the Phillips screwdriver. Pull the plate off the windowsill and place it aside. Close the window.